Primary Total Knee Arthroplasty Revised for Instability: A Detailed Registry Analysis

BackgroundInstability after total knee arthroplasty is a common but poorly understood complication.MethodsData from a large national registry was used to study patient and prosthesis characteristics of 2605 total knee arthroplasty revisions for instability. The cumulative percent revision was calculated using Kaplan-Meier estimates, and Cox proportional models used to compare revision rates. The rate of further revision was analyzed with regard to prostheses used in the first revision.ResultsInstability increased from 6% of all first revision procedures in 2003 to 13% in 2019. The revision risk was lower for minimally stabilized prostheses, males, and patients aged ≥65 years. Polyethylene insert exchange was used for 55% of revision procedures, using a thicker insert in 93% and a change in insert conformity in 24% of cruciate-retaining knees. The increase in either thickness or conformity had no effect on the rate of further revision. After a revision for instability, 24% had a second revision by 14 years. Recurrent instability accounted for 32% of further revisions. A lower second revision rate was seen after revision of both femoral and tibial components, and where constrained components were used.ConclusionRevision for instability is increasing. Revising both femoral and tibial components led to a lower rate of second revision compared to a change in insert alone. Recurrent instability was common.     

One-Surgeon vs Two-Surgeon Single-Anesthetic Bilateral Total Knee Arthroplasty: Revision and Mortality Rates From the Australian Orthopedic Association National Joint Replacement Registry

BackgroundOutcomes following 1-surgeon single-anesthetic sequential bilateral total knee arthroplasty (seq-BTKA) compared to 2-surgeon single-anesthetic simultaneous bilateral total knee arthroplasty (sim-BTKA) are largely unknown. The current study compared revision rates and all-cause mortality following seq-BTKA vs sim-BTKA using data from the Australian Orthopedic Association National Joint Replacement Registry.MethodsSeq-BTKA and sim-BTKA procedures recorded within the registry between September 1, 1999 and December 31, 2018 were analyzed for subsequent revision and patient mortality. Cumulative percent revision and cumulative percent survival were determined using the Kaplan-Meier method. Revision and mortality rates for sim-BTKA and seq-BTKA were compared using Cox proportional hazards models, adjusting for age and gender.ResultsIncluded in the analysis were 27,480 seq-BTKAs and 471 sim-BTKAs. There was no difference in the cumulative percent revision between the 2 groups (hazard ratio 1.23, 95% confidence interval 0.82-1.85). Cumulative percent patient survival was not significantly different between the 2 groups (hazard ratio 1.20, 95% confidence interval 0.93-1.54).ConclusionRevision rates and mortality were similar for seq-BTKA and sim-BTKA. Investigation of additional outcomes such as complications not requiring revision, pain, function, and cost is required to comprehensively understand the relative merits of each procedure.     

Higher mid-term revision rates of posterior stabilized compared with cruciate retaining total knee arthroplasties: 133,841 cemented arthroplasties for osteoarthritis in the Netherlands in 2007–2016

Background and purpose — The preference for a cruciate retaining (CR) or posterior stabilized (PS) TKA (total knee arthroplasty) system varies greatly between Dutch hospitals, independent of patient characteristics. We examined mid-term revision rates for men and women of different age categories.

Patients and methods — We included all 133,841 cemented fixed-bearing primary CR or PS TKAs for osteoarthritis reported in the Dutch Arthroplasty Register (LROI) in 2007–2016. Revision procedures were defined as minor when only insert and/or patella were revised and as major when fixed components (tibia and femur) were revised or removed. 8-year all-cause revision rates of CR and PS TKAs were calculated using competing-risk analyses. Cox-regression analyses were performed, adjusted for age at surgery, sex, ASA -score, and previous operations.

Results — PS TKAs were 1.5 (95% CI 1.4–1.6) times more likely to be revised within 8 years of the primary procedure, compared with CR TKAs. When stratified for sex and age category, 8-year revision rate of PS TKAs in men <60 years was 13% (CI 11–15), compared to 7.2% (CI 6.1–8.5) of CR TKAs. Less prominent differences were found in older men and women. For men <60 years differences were found for minor (CR 1.8% (CI 1.4-2.5); PS 3.7% (CI 3.0–4.7)) and major revisions (CR 4.2% (CI 3.3–5.3); PS 7.0% (CI 5.6–8.7)).

Interpretation — Patients who received a cemented fixed-bearing primary PS TKA for osteoarthritis are more likely to undergo either a minor or a major revision within 8 years. This is especially prominent for younger men.     

Long-Term Implant Survivorship and Modes of Failure in Simultaneous Concurrent Bilateral Total Knee Arthroplasty

BackgroundThere is limited evidence describing long-term implant survivorship and modes of failure in simultaneous concurrent bilateral total knee arthroplasty (TKA).MethodsWe performed a retrospective review of 266 consecutive patients (532 knees) who underwent simultaneous concurrent bilateral TKA. We reviewed medical records for preoperative characteristics, perioperative complications, and revision surgeries. The primary outcome was TKA survivorship. Secondary outcomes included indication and type of revision surgery. We used the Kaplan-Meier method to estimate survivorship and characterize risk of revision up to 20 years post-TKA.ResultsOur cohort had median follow-up of 9.8 years (interquartile range, 3.9-15.9). Forty-four patients (17%) underwent revision. Revision was more common among younger and male patients. The cumulative incidence of first-time revision per knee (n = 532) was 1.27 per 100 component-years. Implant survival was 99% (confidence interval, 97%-99%) at 5 years, 92% (89%-95%) at 10 years, 83% (77%-87%) at 15 years, and 62% (50%-73%) at 20 years. Five and 10-year survivorship compared favorably to estimates of TKA survivorship in the literature. The cumulative incidence of revision surgery per patient was 1.91 per 100 component-years. Implant survival at 5-, 10-, 15-, and 20-year time points was 96% (CI, 92%-98%), 84% (77%-89%), 71% (62%-79%), and 59% (46%-70%), respectively. Aseptic loosening (40%), polyethylene wear (34%), and infection (11%) were the most common indications for revision.ConclusionSimultaneous concurrent bilateral TKA is associated with a higher risk of reoperation for the patient when both knees are evaluated but similar implant survivorship to the literature when each knee was evaluated in isolation.     

Design Modifications of the Posterior-Stabilized Knee System May Reduce Anterior Knee Pain and Complications Following Total Knee Replacement

Background

In total knee arthroplasty (TKA), advances in posterior-stabilized (PS) knee implant designs address patellofemoral mechanics and cam–post engagement in an effort to reduce patellofemoral pain and improve knee kinematics. Such modifications may include improved femoral rollback, improved femoral dislocation resistance, minimized wear, and improved longevity.

Questions/Purposes

In this study, we compared a newer PS knee design that incorporates a left and right specific femoral component and smoother trochlear groove to improve patellofemoral mechanics with an older PS design in order to assess patellofemoral pain, manipulation rates, and revision rates.

Methods

Using an institutional database, we retrospectively identified TKAs performed by the same surgeon using the Logic^® PS knee system and the older Optetrak PS knee system (Exactech Inc., Gainesville, FL, USA), with a minimum 2-year follow-up. Clinical outcomes for each cohort were measured using the Knee Society Clinical Rating System, University of California Los Angeles Activity Scale, pain visual analog scale (VAS), Veterans Rand 12-Item Health Survey, and Western Ontario and McMaster Universities Osteoarthritis Index. In addition, rates of anterior knee pain, manipulation, and revision were compared between the two knee systems, and a Kaplan–Meier survivorship curve defining failure as need for revision was calculated to allow comparison between the cohorts.

Results

From 2000 to 2018, there were 1482 TKAs performed using the Logic PS (not counting 12 patients who had died) and 445 in the Optetrak PS group (not counting 20 patients who had died). In the Logic PS and Optetrak PS groups, respectively, the average age at operation was 66.7 years and 68.6 years and the average body mass index was 30.8 and 31.2. Pain VAS scores were significantly lower in the Logic PS group than in the Optetrak group (1.72 vs. 2.75 out of 10, respectively). There was also a significant difference in the percentages of patients reporting anterior knee pain in the Logic group, as compared with the Optetrak group (5.6% vs. 11.8%, respectively). In addition, manipulation rates differed significantly between the Logic and Optetrak groups (0.34% vs. 10.70%, respectively). The revision rates were 1.15% for the Logic group and 2.0% for the Optetrak group. However, there was a significant difference in rates of revision performed because of osteolysis, favoring the Logic group (0.07% vs. 0.6%). The Kaplan–Meier survivorship curve shows a significant difference in time until revision between the Logic and Optetrak groups.

Conclusion

Design modifications to improve patellofemoral mechanics demonstrated significant improvements in overall pain and patellofemoral pain and reduced manipulation rates post-operatively.

     

Functional Outcomes are Comparable Between Posterior Stabilized and Cruciate-Substituting Total Knee Arthroplasty Designs at Short-Term Follow-up

BackgroundPosterior stabilized (PS) polyethylene inserts have been shown to have excellent long-term functional results following total knee arthroplasty (TKA). A cruciate-substituting (CS) design has been introduced to minimize bony resection and eliminate concerns regarding wear on the PS post. The purpose of this study is to compare the outcomes of patients who underwent TKA using either a PS or CS insert.MethodsWe reviewed a consecutive series of 5970 patients who underwent a cruciate-sacrificing TKA and received either a PS (3,314) or CS (2,656) polyethylene liner. We compared demographics, Knee Injury and Osteoarthritis Outcome Score Jr (KOOS Jr), Short-Form 12 (SF-12) scores, and revision rates between the groups at a minimum 2 years followup. A multivariate regression was performed to identify the independent effect of design on functional outcomes.ResultsRevision rates between the groups were comparably low (0.35% for PS vs 0.51% for CS, P = .466) at an overall mean follow-up of 43 months. Patients in the PS cohort had statistically higher KOOS Jr scores at 2 years (69.8 vs 72.9, P < .001). Multivariate regression analysis found CS patients to have lower postoperative KOOS Jr scores (estimate ?2.26, P = .003), and less overall improvement in KOOS Jr scores (estimate ?2.42, P = .024) than PS patients, but neither was a clinically significant difference.ConclusionPatients who undergo TKA with a CS polyethylene insert have comparable functional outcomes and revision rates to those with a PS design at short-term follow-up. Longer follow-up is needed to determine whether CS can match the outstanding track record of PS TKA.     

Evaluating Long Term Outcomes and Survivorship of Cruciate Retaining and Sacrificing Knee Replacements Done for Degenerative Arthritis in Patients Under 55 Years

BackgroundTotal Knee Arthroplasty (TKA) is the gold standard of treatment for end stage arthritis not responding to conservative treatment. With a recent increase in the younger population presenting with osteoarthritis (OA) we undertook this study to evaluate long-term outcomes and survivorship of TKA in this cohort.Materials and MethodsOur study cohort included 328 patients, < 55 years, with OA, who underwent TKA using Cruciate Retaining (CR), and Posterior Stabilized (PS) implants with a minimum follow up of 15 years. Revision surgery was the end point of our analysis and Kaplan–Meier evaluation of survivorship was measured. Knee Society Scores (KSS) and Range of Motion (ROM) were assessed to evaluate outcomes.ResultsSurvivorship of the CR and PS implants with revision as end point, for aseptic loosening was 97.3% and 96%, and revision for all causes was 89.7% and 86.1%, respectively, at 15 years. The outcomes of CR implants were better than the PS cohort in terms of function and survivorship.ConclusionLong term survivorship and outcome analysis of TKA in patients < 55 years showed good results with excellent survivorship, with both CR and PS implants. The CR cohort demonstrated better long-term survivorship, though the difference was not statistically significant. Deep infection and aseptic loosening were the commonest causes for failure.      

Clinical Outcomes in Isolated Tibial Revision With Cruciate Retaining Total Knee Arthroplasty

BackgroundTibial component loosening is one of the most common modes of failure in contemporary total knee arthroplasty (TKA). Limited literature is available on the outcomes of isolated tibial revision with retention of the cruciate retaining (CR) femoral component. The purpose of this study was to determine the results of isolated tibial revisions in CR TKA.MethodsWe identified 135 patients who underwent an isolated tibial revision after a primary CR TKA from our institutional registry between January 2007 and January 2017. The mean time between the primary and revision was 2.9 years (range 0.1-15.4). Revision with a press-fit stem was performed in 79 patients and 56 patients were revised with a fully cemented stem. Patients were evaluated at a minimum of two years using Knee Society Score, Knee Injury and Osteoarthritis Score for Joint Replacement, and radiography. Implant survivorship was determined using Kaplan-Meier survival analysis.ResultsAt a mean follow-up of 5.1 years, there were six (4.4%) repeat revisions: three for periprosthetic infection (2.2%), two for instability (1.5%), and one for a fractured tibial stem (0.7%). The mean Knee Society Score and Knee Injury and Osteoarthritis Score for Joint Replacement increased from 51.6 and 56.1 preoperatively to 90.1 and 89.7 after surgery (P < .001). Survivorship free of repeat revision for any cause was 93.3% at 5 years, and aseptic revision survivorship was 95.8% at 5 years. No implants were radiographically loose.ConclusionIn patients with isolated tibial loosening and a well-fixed and well-positioned CR femoral component, isolated tibial revision provides excellent early to midterm implant survivorship and clinical outcomes with a low risk of instability and recurrent tibial loosening.     

The Outcome of Total Knee Arthroplasty With and Without Patellar Resurfacing up to 17 Years: A Report From the Australian Orthopaedic Association National Joint Replacement Registry

BackgroundPatellar resurfacing in total knee arthroplasty (TKA) remains a controversial issue after more than 4 decades of TKA. Despite a growing body of evidence from registry data, resurfacing is still based largely on a surgeon’s preference and training. The purpose of this study is to provide long-term outcomes for patellar resurfaced compared to when the patella is not resurfaced.MethodsData from the Australian Orthopaedic Association National Joint Replacement Registry (1999-2017) were used for this study. The analysis included 570,735 primary TKAs undertaken for osteoarthritis. Hazard ratios (HRs) and 17-year cumulative percent revision rates were used to compare revision rates between 4 subgroups: minimally stabilized (MS) patellar resurfacing, posterior stabilized (PS) patellar resurfacing, MS unresurfaced, and PS unresurfaced patella. Additional analyses of the patellar implant type and a comparison of inlay and onlay patellar resurfacing were also performed.ResultsFor all primary TKA, procedures where the patella was not resurfaced have a higher rate of revision compared to procedures where the patella was resurfaced (HR, 1.31; confidence interval, 1.28-1.35; P < .001). Unresurfaced PS knees have the highest cumulative percent revision at 17 years (11.1%), followed by MS unresurfaced (8.8%), PS resurfaced (7.9%), and MS resurfaced (7.1%). Inlay patellar resurfacing has a higher rate of revision compared to onlay patellar resurfacing (HR, 1.27; confidence interval, 1.17-1.37; P < .001).ConclusionResurfacing the patella reduces the rate of revision for both MS and PS knees. MS knees with patellar resurfacing have the lowest rate of revision. Onlay patella designs are associated with a lower revision rate compared to inlay patella designs.     

Distal Femoral Replacement for Periprosthetic Fractures After TKA: Australian Orthopaedic Association National Joint Replacement Registry Review

BackgroundDistal femoral replacement (DFR) is a potential treatment option following periprosthetic fracture (PPF) of a total knee arthroplasty (TKA). However, there is limited literature regarding implant survivorship and complication rates. The aim of this study was to examine patient demographics and trends in usage, implant survivorship and modes of failure, and patient mortality following DFR for PPF captured by a national joint replacement registry.MethodsA retrospective registry review was performed using data from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR). In total, 306 DFR were performed for PPF of a known primary TKA. Eighty-five percent of patients were female, and the mean age was 76.4 years. Kaplan–Meier estimates of implant and patient survivorship were performed.ResultsThe number of DFR performed for PPF has doubled over the past five years. The cumulative percent second revision rate at six years was 12%. The most common indications for revision were infection (37%) and aseptic loosening (33%). Patient survivorship after DFR was 97% and 83% at five and ten years, respectively.ConclusionA national registry review has identified the increasing prevalence of DFR for PPF after primary TKA and demonstrated implant survivorship of 88% at midterm follow-up. Surgeons may consider DFR as an acceptable and durable treatment option.Level of EvidenceLevel III – Case Series.     

Superior Survivorship for Posterior Stabilized Versus Constrained Condylar Articulations After Revision Total Knee Arthroplasty: A Retrospective,Comparative Analysis at Short-Term Follow-Up

BackgroundThe decision to use a posterior stabilized (PS) or constrained condylar knee (CCK) articulation in revision total knee arthroplasty (RTKA) has traditionally been based on surgeon preference and knee stability. The purpose of this study is to compare various outcomes and survivorship in RTKA with PS or CCK articulations.MethodsA retrospective comparative study of RTKA with CCK or PS articulations (PS = 106/CCK = 147) was performed with minimum 2-year follow-up. Exclusion criteria were patients with rotating hinged implants or non-CCK/PS constructs. Multivariate logistic regression models were constructed to determine whether implant articulation influenced (1) complications, (2) aseptic loosening, and (3) re-revision. Kaplan-Meier estimates of cumulative implant survival were constructed with revision as the failure variable.ResultsPS articulation was an independent predictor of increased postoperative knee flexion (6.4°, P = .010) and the knee society functional score (10.0, P = .002). Survivorship was significantly reduced for CCK revision articulations when all-cause re-revision was the primary endpoint (P = .0003, log-rank test of equality). The primary reason for re-revision in the CCK cohort was a recurrent/persistent infection of the operative knee (N = 16, 37.2%), followed by aseptic loosening (N = 13, 30.2%). PS articulations conferred a lower likelihood of re-revision (odds ratio [OR] 0.3, P = .001), but articulation design was not associated with complications (OR 0.5, P = .123) or aseptic loosening (OR 2.6, P = .143).ConclusionThe PS articulation when used for appropriate indication conferred superior survivorship for the primary endpoint of all-cause re-revision and overall knee function when compared to the CCK articulation after RTKA. Implant articulation was not a predictor of aseptic loosening or complications.     

Progressive Tibial Bearing Sagittal Plane Conformity in Cruciate-Retaining Total Knee Arthroplasty

BackgroundWe hypothesized that when the posterior cruciate ligament (PCL) is found deficient at total knee arthroplasty (TKA), using an anterior-stabilized (AS) tibial insert would provide similar function and survivorship when compared to using a more traditional cruciate-retaining (CR) bearing when the (PCL) is balanced.MethodsA total of 1731 TKAs were performed using the same TKA design. Of them, 868 TKAs had a standard CR insert implanted (CR-S), 480 TKAs used a lipped CR insert (CR-L), and 383 TKAs used an AS insert. If the PCL was considered nonfunctional or absent, an AS bearing was placed. When the PCL was balanced, a CR-S or CR-L bearing was used. Follow-up was performed using the Knee Society scoring system. Kaplan-Meier survivorship was used with failure defined as aseptic loosening.ResultsAt final follow-up, there were no significant differences in knee flexion, pain, function, or stair scores. Walking scores were significantly lower in the AS group. Posterior instability was higher in the CR-S group, whereas the manipulation rate was highest in the CR-L group (1.7%, 1.3%, and 0% for CR-L, CR-S, and AS groups, respectively). Kaplan-Meier survivorship at 5 years demonstrated no significant difference between the 3 groups (99% 100%, and 99% for CR-S, CR-L, and AS groups, respectively).ConclusionUsing an AS insert provided similar function and 5-year survivorship as compared to using a CR-S and CR-L tibial insert when the PCL was balanced. Using an ultracongruent AS dished tibial component appears to be a reasonable option when the PCL is completely released or found deficient at operation.     

Despite Improved Survivorship of Uncemented Fixation in Total Knee Arthroplasty for Osteoarthritis,Cemented Fixation Remains the Gold Standard: An Analysis of a National Joint Registry

BackgroundTotal knee arthroplasty (TKA) numbers are increasing worldwide. While cement fixation for both femoral and tibial components is commonly used, alternatives include hybrid and uncemented TKAs. This study aimed to evaluate survivorship, revision rates, and patient-reported outcomes for cemented, hybrid, and uncemented TKAs using New Zealand Joint Registry (NZJR) data.MethodsNZJR data relating to all TKAs performed during the 19 years up to the end of December 2017 were analyzed. Outcomes were assessed using prosthesis survivorship data (including reasons for revision) and Oxford scores at 6 months, 5 years, and 10 years postoperatively.ResultsA total 96,519 primary TKAs were performed during the period examined. Most (91.5%) were fully cemented with 4.8% hybrid and 3.7% uncemented. Mean Oxford scores at 6 months were highest in cemented and lowest in uncemented TKAs (P < .001). However, this was not clinically significant. There was no difference at 5 or 10 years. Ten-year survival rates were 97%, 94.5%, and 95.8% for cemented, uncemented, and hybrid TKAs, respectively. Revision rates were 0.47, 0.74, and 0.52 per 100 component years for cemented, uncemented, and hybrid prostheses, respectively. The revision rate for uncemented prostheses compared with cemented was higher (P < .001). When stratified by age group, there were differences in survival rates between cemented and uncemented groups (P = .001) and hybrid and uncemented groups (P = .038) in patients aged <55 years; between cemented and uncemented groups in those aged 55-64 years (P = .031); and between cemented and hybrid groups in those aged >75 years (P = .004).ConclusionUncemented TKAs had similar patient-reported outcomes but higher revision rates and worse survivorship compared with hybrid or fully cemented TKAs.     

Comparison of Functional Outcomes,Femoral Rollback and Sagittal Stability of Anterior-Stabilized Versus Posterior-Stabilized Total Knee Arthroplasty: A Systematic Review and Meta-analysis of Randomized Controlled Trials

PurposeTotal knee arthroplasty (TKA) has improved leaps and bounds in terms of design to improve clinical outcomes and achieve better rehabilitation of the patients. Ultra-congruent inserts (UC) were designed to replace the need for posterior stabilized (PS) implants. The purpose of this review was to evaluate clinical outcomes, femoral rollback, functional scores, range of motion, sagittal laxity, complication rates, and isokinetic performance between UC and PS TKA among RCTsMethodsElectronic databases such as PubMed, Scopus, opengrey, and Cochrane were searched from date of inception up to mid-April 2021, and meta-analysis was performed following PRISMA guidelines. This study analyzed outcomes, femoral rollback, tibial sagittal laxity and isokinetic performance.ResultsTen RCTs identified 852 knees, of which 420 underwent UC TKAs and 432 underwent PS TKA. Compared to UC TKA, a significantly better sagittal stability (p = 0.17) and femoral rollback (p < 0.00001) in PS TKAs was noted, although no statistically significant difference was found in the assessment of the range of motion (p = 0.19) and functional scores. Both the groups had similar isokinetic performance with extensor torque (p = 0.97) and flexor torque (p = 0.37).ConclusionsWe conclude with the current meta-analysis that there are no added benefits for UC over PS inserts and these inserts have a higher sagittal laxity and less femoral roll back in cruciate sacrificing UC knee. But since there are no long-term wear data, UC inserts with CS technique should be used cautiously and may be used only when the PCL cannot be balanced adequately. There is no evidence or only a few to support the superiority of the AS TKA in terms of clinical outcomes or isokinetic performance or femoral external rotation over PS TKA.Level of EvidenceLevel I, Systematic review and meta-analysis of RCTs.     

Retrieval Analysis of Cruciate-Retaining and Posterior-Stabilized Total Knee Arthroplasty and Correlations to Laxity and Wear

BackgroundTotal knee arthroplasty (TKA) with posterior-stabilized (PS) or posterior cruciate-retaining (CR) implants has high success rates and survivorship. However, it is uncertain how laxity and constraint are associated with long-term polyethylene wear under physiological conditions.MethodsTo answer this question, we measured the laxity patterns of 47 harvested cadaver specimens with primary TKAs in a custom knee-testing machine at full extension and at 30°, 60°, and 90° of flexion. The wear patterns of the tibial inserts were assessed using a semiquantitative method which is a modified approach of that proposed by Hood et al in 1983.ResultsStatistical analysis found that the PS TKA cohort had a statistically significant increase in varus laxity at 60° and 90° of flexion, as well as total coronal laxity at 60° of flexion when compared to the CR cohort. Furthermore, analysis demonstrated a significant correlation between increased PS coronal laxity and increased tibial wear, a trend that was not seen in the CR specimens.ConclusionOur findings suggest that greater laxity in flexion after primary TKA may increase the wear realized over time and that PS TKAs may be more susceptible due to the loss of support the PCL affords to the flexion space. Whether a CR or PS TKA is used, surgeons need to avoid the pitfalls that may create greater flexion laxity during the procedure to optimize long-term polyethylene wear.     

Revision Total Knee Arthroplasty Using an Uncemented Metaphyseal Sleeve,Rotating Hinge Prosthesis: A Case Series of 99 Patients

BackgroundHinge knee replacement is a salvage procedure with historically high failure and complication rates. We aim to analyze the use of an uncemented metaphyseal sleeve revision knee replacement in our unit—a third-generation rotating hinge knee prosthesis. This is the largest reported series of this implant with longest follow up.MethodsWe retrospectively identified 99 revision cases performed (2002-2018). In total, 67 of 99 (68%) cases were performed for aseptic etiology, whereas 32 of 99 (32%) cases were performed for infection. Clinical outcomes were assessed using the Oxford Knee Score, survivorship analysis, and incidence of revision/reoperations. Mean follow-up was 7 years (range 1.5-18).ResultsAt follow-up, the mean Oxford Knee Score had improved from 10 points to 25 points. At mean 7 years of follow up, 18 of 99 cases had undergone revision giving a survivorship of 81% (90% aseptic). In total, 10 of 18 cases were performed for infection (10%) and 9 of 18 cases were performed for aseptic reasons (9%), of which 5 were for patella resurfacing (2 revision), 2 for failure of bony ingrowth, and 1 for fracture. Twenty-six patients (26%) had complications postoperatively, with patella disorders and reduced range of movement the most common. Patients who did not undergo patella resurfacing were significantly more likely to need revision of any cause (P = .01).ConclusionThis is the largest study of this prosthesis with longest follow-up. It demonstrates good survivorship and improvement in knee pain. Those with infection are at greatest risk of revision. Significant numbers have patella dysfunction/anterior knee symptoms therefore patella resurfacing should be considered when using this implant.Level of EvidenceIV.     

Similar Risk of Revision After Kinematically Aligned,Patient-Specific Instrumented Total Knee Arthroplasty,and All Other Total Knee Arthroplasty: Combined Results From the Australian and New Zealand Joint Replacement Registries

BackgroundKinematic alignment (KA) in total knee arthroplasty (TKA) replicates individual knee joint line orientation and physiological soft tissue balance. There are limited data on the effect of KA on survivorship compared with other methods of implanting a TKA. The aim of this study was to compare the survivorship of the same design of TKA implanted with either patient-specific instrument (PSI) KA or with computer-assisted surgery and conventionally instrumented.MethodsWe performed an observational study of data from 2 national joint registries on all patients who underwent a TKA with a Triathlon cruciate-retaining TKA (Stryker, Mahwah, NJ) from January 2011 to December 31, 2013. The outcomes of knees performed with unrestricted KA using patient-specific instrument were compared with computer-assisted surgery and conventionally instrumented Triathlon cruciate-retaining TKA. The principal outcome measure was time to first revision using Kaplan-Meier estimates of survivorship. Cox proportional hazard ratios, adjusted for age and gender, were used to compare the 2 groups.ResultsThere were 20,512 TKA procedures recorded, of which 416 were performed using KA-PSI. The KA-PSI group was younger (66.8 ± 8.2 vs 68.3 ± 9.2, P = .001), with an identical gender distribution. The cumulative revision rate at 7 years was 3.1% for the KA-PSI Triathlon cohort and 3.0% for the other Triathlon TKA cohort (P = .89). The most common reasons for revision in the KA-PSI group were maltracking, patella erosion, and arthrofibrosis.ConclusionKinematically aligned Triathlon TKA using PSI has similar revision rate as all other Triathlon TKA.     

Advantage of Minimal Anterior Knee Pain and Long-term Survivorship of Cemented Single Radius Posterior-Stabilized Total Knee Arthroplasty without Patella Resurfacing

BackgroundThe single radius total knee prosthesis was introduced with the advantage of reduced patellar symptoms; however, there is no long-term follow-up study of the same. The purpose of this study was to determine the survival rate of single radius posterior-stabilized total knee arthroplasty and patellofemoral complication rates in a consecutive series.MethodsSeventy-one patients (103 knees) who underwent arthroplasty without patellar resurfacing using a single radius posterior-stabilized total knee prosthesis were followed up for a minimum 10 years. Clinical evaluation using Knee Society knee and function scores and radiologic evaluation were performed at regular intervals. Anterior knee pain as well as patellofemoral complications were evaluated with a simple questionnaire. The Kaplan-Meier product-limit method was used to estimate survival.ResultsSeventeen patients (23 knees) were excluded due to death (12 knees) or lost to follow-up (11 knees). Of the 80 knees enrolled, all femoral components and 78 tibial components were well fixed without loosening at final follow-up. Two revisions were performed because of tibial component loosening and periprosthetic joint infection. One patient with tibial component loosening refused to have revision surgery. No obvious tibial insert polyethylene wear was observed. The survivorships at 132 months were 96.7% using revision or pending revision as end points. Anterior knee pain was present in 6 patients (6 knees, 7.5%) at the latest follow-up. No patellofemoral complication requiring revision was encountered.ConclusionsThe single radius posterior-stabilized total knee prosthesis demonstrated an excellent minimum 10-year survivorship. The low rates of implant loosening and 7.5% of anterior knee pain as a patellofemoral complication are comparable with those reported for other modern total knee prosthesis.     

Use of National Joint Registries to Evaluate a New Knee Arthroplasty Design

BackgroundThe introduction of new technology in joint replacement surgery requires close monitoring to identify early successes and failures. This monitoring can be effectively performed through the analysis of registry data and radiostereometric analysis studies. This study examined the revision rates of a contemporary knee system for total knee arthroplasty (TKA) using National Joint Replacement Registries.MethodsA review of the literature was performed to identify comparative studies and registry databases reporting the revision rates of a specific contemporary knee design between 2013 and 2018. The total number of TKA cases performed using this implant was recorded. The latest follow-up or duration of monitoring through a registry database was used to report implant survivorship.ResultsThere were 4 registry databases and 1 comparative study reporting the revision rates of the contemporary knee system. A total of 41,483 cases were identified with a follow-up range of 1.5-5.0 years. The all-cause revision rate ranged from 0.7% to 2.5% at latest follow-up. This was comparable to all-cause revision rates of other knee systems reported in the registries, ranging from 0.8% to 5.6% over similar follow-up periods.ConclusionsEvaluation of data from multiple national joint registries demonstrated the revision rate for this contemporary knee system to be comparable to other TKA systems at latest follow-up. None of the registries have identified any concerning rates of revision compared to other devices at this length of follow-up. National Joint Registries are an important resource in evaluating the short-term, mid-term, and long-term results of new implant designs introduced to the market.